Low-power MCU electronic circuit design atlas TOP12 - circuit diagram reading every day (110)

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

Shunluo Inductance Power Inductor SWPA Series First Class Agent

1.5PF SOT23-6 Low Capacitance 5V Breakdown Voltage 6V SRV05

TOP1 STM32 low cost WiFi playback circuit

Using STM32F103 as a microprocessor, design a low-cost wireless WiFi music playback system, combined with WM-G-MR-08 (wm631) module and VS1003B audio decoder that receive WiFi data to achieve MP3 music playback. The client software developed based on the Android system uses mobile phone control to complete the data transmission between the mobile terminal and the control terminal, and realizes the remote control of the music player by the mobile phone. The results show that the system is simple and convenient, low cost, reliable and easy to expand. This design is based on the already mature WiFi wireless network, making full use of the advantages of wide WiFi coverage, fast transmission speed and strong anti-interference ability. Android has the advantages of open source, encapsulation, and high cost performance. The client software developed based on Android system has strong portability and high versatility. The mobile phone is used as a control terminal for easy operation. The mobile phone controls the music playing system through the wireless network (WiFi), which can realize convenient, fast and intelligent requirements.

Audio decoding module

The VS1003B is a single-chip MP3/WMA/MIDI audio decoder and ADPCM decoder. It includes a high-performance, proprietary, low-power DSP processor core, VS_DSP4, which provides 5KB of instruction ROM and 0.5KB of data RAM for user applications. It also features a serial control and data interface, a high quality variable sample rate ADC and stereo DAC, four general purpose I/O ports, a UART, and a ground buffer and headphone amplifier.

The STM32F103 transmits the MP3 audio data stream read from the SD card to the audio decoding module, and the audio decoding module parses and converts the data stream into an analog signal before outputting. Data communication between the VS1003B and the STM32F103 is via the SPI bus on the J2 header.

WiFi wireless module

The biggest advantage of WiFi (Wireless Fidelity) is that the transmission speed is high, and the bandwidth can be automatically adjusted, which can effectively ensure the stability and reliability of the network. The WM-G-MR- 08 module used in this design not only has the function of WiFi, but also provides a small size and high data rate wireless connection for wireless PDA, DSC, media adapter, micro printer, barcode scanner, VOIP Telephone, etc. The data storage device is a potential application of the WM-G-MR-08, and the embedded application is mainly focused on the mobile device. In the design, the WM-G-MR-08 module communicates with the main control chip through the SPI pin of the J1 pin header on the development board, and the ANT1SMACON is a wireless network card. The schematic diagram is shown in Figure 2.

This design is to build WiFi on the ARM7 platform, and the cost advantage is obvious. Adopting the newer control method—smartphone software control + wireless network, not only can make full use of the advantages of fast transmission speed and wide coverage of WiFi, but also the construction cost of Android-based platform is low and easy to use. At the same time, the mobile phone software adopted in this way has universality, high market application value, easy to promote, and can provide users with high quality, convenient and fast music broadcasting service.

Application of single chip in ultrasonic ranging

The working principle of the system: the square wave signal of 40 kHz frequency is sent by the microcomputer to the signal processor. The signal processor transmits the signal through two stages of amplification, and then the piezoelectric transducer transmits the signal, and the signal is reflected back by the obstacle. This is called an echo. At the same time, the piezoelectric transducer sends the received echoes to the microcomputer for processing by signal amplification, integral shaping and processing of a series of common circuits. The sound alarm frequency of the display, the orientation indication of the LED and the distance display of the obstacle from the ultrasonic probe are all controlled by the single chip microcomputer.

For the 12-point circular linked list, find the average of the measured values ​​of each ultrasonic probe four times to reduce the error, and then compare the average of the three probes. The minimum value is the time required for the nearest obstacle to reflect back the echo. The electrical schematic is shown in Figure 2, where P3. 4 in Figure 2 is the SYNC synchronization cycle terminated by the CL K terminal of a cyclic shift counter, and the Q0, Q1, Q2 outputs respectively control three ultrasonic transducers to make it alternate. The working, circuit diagram and working waveform are shown in Figures 3 and 4.